Method for the production of plastic

ABSTRACT

Plastic covered coils which are compact and easily inserted in a circuit board are efficiently and economically produced by a continuous production method wherein a generally tubular core having a winding thereon is plugged onto a mounting rod portion of a transporting belt and has the coil ends connected to a upper portion of the belt, a coating of plastic is applied over the coil sub-assembly, the upper discontinuous portion of the band is separated from the lower continuous portion, and the contacts formed as required. An enlarged base formed by the plastic coating may contain coil control components.

Utner June 12, 1973 METHOD FOR THE PRODUCTION OF PLASTIC [75] Inventor:Ferdinand Utner,Regensburg,

Germany v [73] Assignee: Siemens Aktiengesellschaft, Berlin &

Munich, Germany [22 Filed: Nov. 18, 1971 21 Appl. No.2 200,124

[30] Foreign Application Priority Data Nov. 19, 1970 Germany P 20 56909.9

[56] References Cited 7 UNITED STATES PATENTS Zerwes 336/192 X Franz336/192 3,590,480 7/1971 Johnson, Jr. et a1 29/605 3,625,350 12/1971 Ray29/628 X FOREIGN PATENTS OR APPLICATIONS 950,803 2/1964 Great Britain336/192 Primary Examiner-Charles W. Lanham Assistant Examiner-Carl E.Hall AttorneyHill, Sherman, Meroni, Gross & Simpson [5 7] ABSTRACTPlastic covered coils which are compact and easily inserted in a circuitboard are efficiently and economically produced by a continuousproduction method wherein a generally tubular core having a windingthereon is plugged onto a mounting rod portion of a transporting beltand has the coils ends connected to a upper portion of the belt, acoating of plastic is applied over the coil sub-assembly, the upperdiscontinuous portion of the band is separated from the lower continuousportion, and the contacts formed as required. An enlarged base formed bythe plastic coating may contain coil control components.

8 Claims, 7 Drawing Figures PATENIEU M 3. 737. 995

sum 2 or z INVENTOR fraznand' U/ner' METHOD FOR THE PRODUCTION OFPLASTIC BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention generally relates to a method for the substantiallycontinuousproduction of generally cylindrically shaped plastic covered coilshaving a pluggedtype electrical connection useful in circuit boardswhere they are plugged inon one end and upstand vertically. Morespecifically the coils have a tubular core through which one of thewinding wires is run and into which an upstanding mounting rod isinserted so that continuous production is facilitated. A coating ofplastic insulating material may be of varying thickness along the lengthof the coil to provide portions thereof with different diameters inaccordance with application requirements.

2. Prior Art The use of plurality of similar or identical coils inprinted circuit board constructions used in electronic applications suchas fixed value memories, requires that the field of electrical currentsflowing through the different coils does not become so large as to causeinduction voltages in windings on adjacent cores since these inductionvoltages might effect their operation. The coils thuS must have a closedmagnetic coupling between the 'conductor paths and the windings on thecoil cores, i.e., the distance between the core and the conductor pathmust be kept as small as possible. In this type of construction it isusually necessary that rod cores be arranged among the coils in order toguide the lines of the induction fields emerging from the coil corestowards the other side of the coil on well defined paths.

According to prior art methods of making coils a small semi-conductorplate is set onto a corresponding surface of a small carrier plate andattached thereto by gluing or welding their contacts onto other stripswhich are provided,for this purpose.

These prior art methods present difficulties when applied to theconstruction of wound coils. Thus, the sheet metal strips lie along thecoil and not only influence the output of the coil but represent adanger to the fine wire of the winding. For example, the GermanGebrauchmuster Pat. No. 1,887,373 describes a cylindershaped resistorwith one cap or clamp respectively at each of its two opposite endswhereby at least one of the caps or clamps is connected with atransporting band means in one piece, during the production process.This method, however, has a severe disadvantage that the cap representsa short circuit winding which could possibly weaken the signals to betransmitted. Another disadvantage is that one of the laterallyprojecting solder contacts must be slipped over the coil and guidedtoward the printed circuit thereby requiring that a relatively largedistance be provided between the winding which has been placed aroundthe component part and the core after the structure has been coated tobecome a cylindrical component part. Furthermore, the magnetic couplingbetween the outer winding and that one which is applied to the corewould be very bad with this construction since it would cause a stronginfluencing of adjacent coils. In addition, providing for connections onboth sides of a coil member as illustrated herein it is very difficultaccording to the prior art and requires complicated embossmentsand'metal working. This is especially true if only one transporting beltmeans is to be used for the production of both contacts.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to overcome the disadvantages of the prior art by providingfor the production of cylindrically shaped coils in series which coilshave a contact means only on one end and have thin connection wires, inthe order of one-tenth of one millimeter diameter, which must beconnected mechanically safe and electrically conductive to feed lines.According to the invention this advantageous method comprises the stepsof winding an elongated tubular core with an outer wire winding of atleast one wire, positioning one end of the wire winding so that itextends through tubular core whereby the first and second ends of thewire winding are at a first end of the tubular core, mounting thistubular wire wound core on a projecting portion of a transporting beltmeans, said belt means having an outer portion which,

when separated therefrom, may serve as first and second contact means,connecting the first and second wire ends to separate ones of thecontact means, applying a coating generally over the surface of the coilaccept for portions of the contact means, and separating the outerportion of the transporting belt means to form the coil means.

This method has the advantage of avoiding mechanical stress on the coilduring the electrically conductive connecting with the contact surfaces,during the coating of the coil, and during the later insertion into theelectrical circuit. Another advantage is that the coils are held by theprojecting portion or mounting rod projection without a necessity forenlarging the core elements circumference at various places as was truein the prior art. Moreover, the rectangular cross section of themounting rod projection results in the advantage that while on the onehand, it can be adapted exactly to the tubular core diameter, it does onthe other hand, leave sufficient space to allow threading one end of thewire winding through the core.

1 The coil is generally cylindrically shaped with a first end of thecoil including an enlarged base portion having first and second laterialprojections which projections are of a different width are of a widthless than a diameter of the cylindrical portion. The first and secondprojections are each adjacent a contact means. The lateral projectionforms a pedestal which may have embedded therein during the coating stepone or more component control elements. With this construction eachcontact surface of the cylindrically shaped coil has a lateralprojection of different width cooperating therewith so that the contactsmay be easily and accurately positioned in the circuit board. A furtherfeature which is economically incorporated in the coil construction andwhich avoids adjusting devices when the completed coil is, inserted intothe circuit board includeS a stop which is formed by the free part ofthe contact surface being preferably bent at a right angle to theremainder of the contact surface.

A transporting belt means according to the invention contains aplurality of spaced mounting rod projections extending from one edge ofa strip-like member. The mounting rod projection may be of a rectangularcross section taken transverse to the axis thereof. A slit is providedadjacent the mounting rod projection and extends inwardly from the edgewhereby when the transporting belt means 'iscut along a line inwardlyand roughly parallel to the edge the mounting rod projections will beseparated from the transporting belt means and the portions of thetransporting belt means adjacent the slits will serve as contactsurfaces. At least one opening may be cut into the contact surfaces inorder to obtain a better mechanical connection between the coating andthe contact surfaces. Since the mounting rod projection remainsconnected with a contact surface the corresponding end of the coil wiremay be welded to the projecting pieces of the rod to guarantee aparticularly good electrical connection. With this design of thetransporting belt the contact surfaces will be separated from each otherand the coils may be separated from the transporting belt by means ofonly one cut. The contacts or contact surfaces are held in the plasticcoated base or pedestal in a stable relationship due to the openings inthe contact surfaces which the plastic coating will penetrate during thecoating process. In a further embodiment of our invention the projectingportion of the transporting belt means may be provided with an internallongitudinally extending slit dividing the projecting portion into firstand second parts, which parts are bent away from each other to provide amore stable connection and support for the core during the manufacturingprocess.

If both coils and unwound rod cores are required, the transporting beltmeans may be designed to have a first and second separated portion whosedistance of separation is adapted generally to the length of the .coilsand the rod cores. With this construction the second portion of the beltmay have an inner edge with a plurality of spaced mounting rodsprojecting towards the second portion and the second portion may have aninner edge with a plurality of spaced mounting supports generallyprojecting toward the first portion. The inner edge of the first portionmay have indentations therein receiving an end of the coil core. Thefirst and second portions have slits extending inwardly from the inneredges adjacent each mounting rod projection and mounting support wherebywhen the first and second portions are cut along a line inwardly of andgenerally parallel to the inner edges it will result that the mountingrods and the mounting supports will be separated from the transportingbelt means. A transporting belt means of this design has the advantageof providing particularly good guidance of the coil and rod core becauseof their cenral balanced relationship to each other. It also allows aparticularly good utilization of the belt material and allows theseparation of the rod core as by means of a first cut along a separationline in the second portion and a simultaneous separation of the coils bya second cut along a separation line in the first portion. The mountingrod projections and mounting supports may be attached in groups ofparticular sizes and may be arranged in predetermined groups inaccordance with the number of coils or rod cores respectively requiredin a particular application. This greatly facilitates their packingand/or storage.

The mounting support for the rod core on the transporting belt secondportion may take the form of a genj the T-shaped member. An adequatesupport for the rod core is provided by bending the cross member of theT-shaped member into a generally circular shape portion and bending theleg at right angles to its initial position whereby the leg serves as astop for the unwound core when it is inserted into the circular shapeportion.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects; features and advantagesof the invention will be readily apparent from the following descriptionof certain preferred embodiments thereof, taken in conjunction with theaccompanying drawings, although variations and modifications may beeffected without departing from the spirit and scope of the novelconcepts of the disclosure and in which:

FIG. 1 is an elevational view of the coil sub-assembly about to beattached to a transporting belt means wherein the coil is shown in crosssection to illustrate how the'connection wire is guided through theopening of the central core member;

FIG. 2 is an elevational veiw of the belt having a coil, shown in crosssection, which has been produced accordingto the method of the inventionbefore the excess portion of the transporting belt means has beenseparated;

FIG. 3 is a top view of a completed coil assembly illustrating anexaggerated base construction having lateral projections of differentsizes with control elements embedded therein;

FIGS. 4 and 5 illustrate a further embodiment of the mounting rodprojection of the transporting belt having an internal slit dividing theprojecting portion into first and second parts which are bent away fromeach other;

FIG. 6 illustrates another embodiment of a transporting belt meansaccording to the invention wherein a recess on a first portion holds afirst end of the core and a mounting rod extension on a second portionof the transporting belt holds a second end of the core; and,

FIG. 7 is a top view of just the mounting support of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 there maybe seen a generally elongated coil means generally indicated at 35 whichincludes a tubular core 1 surrounded by at least a single layer winding2 of a single piece of wire having a first end 3 and a second end 6. Asshown, the first end 3 of the wire forming the coil 2 is threadedthrough the tubular core member 1 to provide for both ends of the wireat the first end la of the core 1. As may be seen from a comparison ofFIGS. 1 and 2, the tubular core l is forced over a projecting rod means4 which rod means is initially integral with a transporting belt means5. The transporting belt means 5 has indentations 36 and 37 adjacent themounting rod projection 4 which indentations are generally of a width toreceive the first end la of the core member 1. A plurality of slits 7extend'inwardly from an edge 5a of the transporting belt 5 a distancesufficient to extend below a separating cutting line-29. Thetransporting belt means 5 includes contact surfaces 8 and 9 situatedbetween the slits 7 which contact surfaces have connected thereto thesecond and first ends of the wire 6 and 3, respectively. Thus, thesecond end 6 may be welded to the contact portion 8 and the first end ofthe coil wire may be welded to the contact portion 9. Suitable holes 13and 15 may be provided in the contact portions 9 and 8, respectively,and the wire ends 3 and 6 may be passed therethrough prior to welding toeffect a superior electrical connection between the wires and thecontacts 8 and 9.

With the tubular wire wound core 35 mounted on the projecting portion 4and the first and second ends of the wire electrically connected to thesecond and first contact portions respectively, the tubular core and aportion of the contact portions 8 and 9 are coated with a plasticelectrically insulating material to form a covering generally indicatedat 10. The material may be sprayed on with or without a mold. Thecoating 1 serves to provide a mechanical protection of the wind 7 ings,of the thin connection wires 3 and 6 (which may be in the order of 1/1 0of a millimeter in diameter) and of their connection to the contactportions 8 and 9. By means of this method the upper cylindrical portion11 of the coil has as small a diameter as possible necessary to meetproduction tolerances. On the other hand, the

. width, which width is less than the diameter of the centralcylindrical portion 12, so that the completed coil 35 may be easily andaccurately plugged into a circuit board. Thus, the first laterallyextending portion of the base 27 may have a width a whereas the secondportion 32 may have a width b so that when the coil is plugged by meansof its first end and contacts into a mounting board the contacts will beproperly oriented. As shown in FIG. 3 the lateral projections 27 and 32may be enlarged to include embedded component coil control elements 40and 41, respectively. These component control elements may be a resistorand/or a diode which, when embedded in the base during the process ofmaking the coil, provide a lower interference sensitivity of the controland a more simple circuit arrangement.

As shown in FIG. 1 the first wire end 3 may be welded at either ofpoints 13 and 14 on the contact portion 9. The point 13 has theadvantage that it is on about the same latitude as the point on thecontact portion 8 and thereby lends itself better to an automaticwelding arrangement. On the other hand, the point 14 is at theconnection point of the mounting rod projection 4 and thereby guaranteesa particularly small free wave length of the connection wire 3. The wire3 of course has been shielded by the core 1 throughout its length andthis construction is particularly advantageous for thin wires.

The slits 7 in the band 5 extend below a separation cutting line 29 sothat the contact portions 8 and 9 are separated from each other and fromthe remainder of the belt 5 with only one cut along the separation line29. As will be most clearly seen in FIG. 2 the coating may extend intothe slit 7 to provide a positive insulation between the portions 8 and9. Also, it will be seen that the contact portions 8 and 9 each includetherein a hole means 39 through which the coating 10 will extend to lockthe contact portions 8 and 9 securely in place. Whereas the contactportion 9 will be securely held by the portion of the projecting rod 4which will remain in place, the contact portion 8 will benefit from theprovision of the hole 39.

In place of the contact portions 8 and 9 as shown in FIG. 1, there maybe provided contact means 16 and 17 as shown in FIG. 3. In the latterembodiment the contact surfaces 16 and 17 may be bent at a generallyright angle either at the beginning of the method of making the coil oralternatively after the coil has been separated from a transporting rod5. The bent portions serve as a stop means to limit the distance whichthe coil may be inserted into the circuit board.

According to an embodiment of the invention as shown in FIG. 4 theprojecting portion 19 of the transporting belt means may be providedwith an internal slit 20 dividing the projecting portion 19 into a firstpart 21 and a second part 22 which parts 21 and 22 are bent away fromeach other to provide an enlargement of the projecting rod portion. Whenthe core 1 is positioned on this projecting portion it may be seen thatgreater stability may be provided while at the same time allowing thewire 3 to be threaded through the tubular core.

In lieu of the transporting belt means 5, a two sided transporting beltgenerally indicated at 23 in FIG. 6 may be provided which consists offirst and second portions 33 and 34, respectively, that are spaced aparta distance generally equal to the length of a tubular core member 1 asschematically illustrated in dotted lines. This construction isparticularly useful where both wound coils 35 and unwound rod cores suchas shown at 1 are needed in the circuit. In this construction the firstportion 33 of the transporting belt means has an innei' edge 33a with aplurality of indentations therein for receiving a first end la of therod core 1. In addition slits 7 as shown with respect to the belt 5 mayalso be provided. The second portion 34 has an inner edge 34a having aplurality of spaced mounting rods 24 positioned thereon to be receivedin a second end lb of a mounting rod 1. In addition, the second portion34 may have a mounting support means generally indicated at 26 alsoextending from its inner edge 34a and, as shown, spaced between themounting rod projections 24.

The mounting support means 26 is also shown by itself in a top view inFIG. 7. The mounting support member 26 for the unwound broad core takesthe form of a generally T-shaped member consisting of a leg 31 extendingfrom the second portion 34 and having a cross member 30 extending fromthe end thereof remote from the second portion 34. The cross member I 30may be seen in FIG. 7 to be bent in a generally circular configurationto receive the core member therein and the leg 31 is bent at rightangles adjacent its opposite ends whereby the legs serves as a stop foran unwound core when the unwound core is inserted in the circular shapedportion 25. The mounting rod projections 24 as well as the mountingsupport means 26 will be severed from the second portion of thetransporting belt means 34 along a line generally indicated at 28 inFIG. 6 whereby these elements will thus remain with the coils or unwoundrod cores. Thus, the portion 26a of the mounting support means 26 mayserve as a base plug for insertion of the mounting rod core in a circuitboard. The mounting rod cores together with the mounting support 25 willbe coated with a plastic coating in the same process as the adjacentcoils so that the mounting support 25 will be permanently connected tothe rod cores. This two portioned transporting belt 7. means has theadvantage of providing stable guidance of the coil and rod cores throughthe manufacturing process since it serves to secure opposite ends of thecoils and cores. It will be understood that the transporting belt 23 mayhave inner connecting portion 23a extending between the first and secondportions of the belt at intervals therealong to assure stability andconstant spacing. The belt material may be of an electrical conductingcopper of a gauge which supplies sufficient rigidity in accordance withthe coil and core sizes. This material allows a particularly goodutilization of the belt and provides for ease of separation of theprojecting portions inside the cutting lines 28 and 29.

From the foregoing it will be understood that with the belt structure asubstantially continuous production of coils may be effected in a serieswherein the particular size and number may be arranged in predeterminedgroups which groups may correspond to the number of coil means and rodcores required in a particular device. The steps in this method includewinding a tubular core 1 with an outer wire winding of at least one wire2, said wire 2 having a first end 3 and a second end 6, positioning orthreading the first end 3 of the wire winding 2 so that it extendsthrough the tubular core 1 whereby the first and second ends 3 and 6 ofthewire are .at a first end la of the tubular core, mounting thistubular wire wound core 1 on a projecting portion of a transporting beltmeans either by positioning the core first end la over a mounting rodprojection 4 or 19 as shown in FIGS. 1, 2 and 4 or mounting the secondend lbof the rod 1 on the mounting rod projection 24 as shown in FIG. 6,connecting the first and second wire ends 3 and 6, respectively, tocontact portions 8 and 9 of the belt means 5 or 33, applying a coatingof plastic material generally over the surface of the coil and portionsof the contact means 8 and 9 as shown in FIG. 2, which coating may be ofdifferent thicknesses along the length of the coil and may be enlargedto the extent as shown in FIG. 3 to include control components 40 and41, for example, and separating the contact portions 8 and 9 togetherwith the mounting rod projections from the transporting belts 5 or 23along the separating cutting lines 29 and 28 whereby the completed coilsmay be packed and are ready for insertion into the mounting board.

The method further include the steps of providing the projecting portion19 of the transporting belt means with an intemal slit 20 dividing theprojecting portion 19 into a first and second portions 21, 22 andbending these portions away from each other.

Although minor modifications might be suggested by those versed in theart, it should be understood that I wish to embody within the scope ofthe patent warranted hereon all such modifications as might reasonablyand properly come within the scope of my contribution to the art.

I claim as my invention:

1. A method for the substantially continuous production in scries'ofagenerally elongated coil means having first and second ends, said firstend including a base means having contact means thereon comprising thesteps of winding onto a tubular core a plurality of turns of at leastone wire, said wire having a first end and a second end, positioning oneend of the wire winding so that it extends through the tubular corewhereby said first and second ends of the wire winding are at said firstend of said tubular core, mounting this tubular wire wound core on aprojecting portion of a transporting belt means, said belt means havingan outer portions which, when separated therefrom, serve as first andsecond contact means, connecting said first and second wire ends toseparate ones of said contact means, applying a coating generally overthe surface of said coil means except for portions of said contactmeans, and separating said outer portions of said transporting beltmeans from the remainder of said belt to form said coil means.

2. A method according to claim 1 wherein said transporting belt meanscomprises two generally parallel and spaced first and second portions,said second portion of said belt having a mounting rod projectionreceived in said second end of said tubular core.

3. A method according to claim 2 wherein said second portion of saidtransporting belt means additionally contains mounting supports spacedbetween adjacent mounting rod projections, said mounting supports havinga circular portion receiving therein an unwound tubular core, saidunwound tubular core lying between adjacent coil means in generallyparallel relationship thereto, and said method includes the step ofseparating said mounting support from said second portion of saidtransporting belt means.

4. A method according to claim 3 wherein said belt secondportion has agenerally T-shaped member consisting of a leg and a cross memberextending therefrom, said T-shape member being attached to said secondportion by the leg of said T-shaped member, said method including thesteps of bending said cross member of said -T-shape member into agenerally circular shaped portion, and bending said leg at right angleswhereby said leg serves as a stop for said unwound core when saidunwound core is inserted in said circular shaped portion. I

5. A method according to claim 1 wherein said coil is generallycylindrically shaped, said first end of said coil including an enlargedbase portion having first and second lateral projections, saidprojections being of a different width and being less than a diameter ofsaid cylindrical portion, said first and second projections beingadjacent each of said contact means.

6. A method according to claim 1 wherein said con tact means whenseparated from said belt means, has a portion thereof bent at a rightangle thereto whereby said bent portion may serve as a stop means whensaid coil is plugged in a circuit board.

7. A method according to claim 1 including providing said projectingportion of said transporting belt means with and internal slit dividingsaid projecting portion into a first and a second part, and bending saidfirst and second parts away from each other.

8. A method according to claim 5 including the step of embeddingcomponent coil control elements in said lateral projections.

1. A method for the substantially continuous production in series of agenerally elongated coil means having first and second ends, said firstend including a base means having contact means thereon comprising thesteps of winding onto a tubular core a plurality of turns of at leastone wire, said wire having a first end and a second end, positioning oneend of the wire winding so that it extends through the tubular corewhereby said first and second ends of the wire winding are at said firstend of said tubular core, mounting this tubular wire wound core on aprojecting portion of a transporting belt means, said belt means havingan outer portions which, when separated therefrom, serve as first andsecond contact means, connecting said first and second wire ends toseparate ones of said contact means, applying a coating generally overthe surface of said coil means except for portions of said contactmeans, and separating said outer portions of said transporting beltmeans from the remainder of said belt to form said coil means.
 2. Amethod according to claim 1 wherein said transporting belt meanscomprises two generally parallel and spaced first and second portions,said second portion of said belt having a mounting rod projectionreceived in said second end of said tubular core.
 3. A method accordingto claim 2 wherein said second portion of said transporting belt meansadditionally contains mounting supports spaced between adjacent mountingrod projections, said mounting supports having a circular portionreceiving therein an unwound tubular core, said unwound tubular corelying between adjacent coil means in generally parallel relationshipthereto, and said method includes the step of separating said mountingsupport from said second portion of said transporting belt means.
 4. Amethod according to claim 3 wherein said belt second portion has agenerally T-shaped member consisting of a leg and a cross memberextending therefrom, said T-shape member being attached to said secondportion by the leg of said T-shaped member, said method including thesteps of bending said cross member of said T-shape member into agenerally circular shaped portion, and bending said leg at right angleswhereby said leg serves as a stop for said unwound core when saidunwound core is inserted in said circular shaped portion.
 5. A methodaccording to claim 1 wherein said coil is generally cylindricallyshaped, said first end of said coil including an enlarged base portionhaving first and second lateral projections, said projections being of adifferent width and being less than a diameter of said cylindricalportion, said first and second projections being adjacent each of saidcontact means.
 6. A method according to claim 1 wherein said contactmeans when separated from said belt means, has a portion thereof bent ata right angle thereto whereby said bent portion may serve as a stopmeans when said coil is plugged in a circuit board.
 7. A methodaccording to claim 1 including providing saId projecting portion of saidtransporting belt means with and internal slit dividing said projectingportion into a first and a second part, and bending said first andsecond parts away from each other.
 8. A method according to claim 5including the step of embedding component coil control elements in saidlateral projections.